Some hobbyists consider sea cucumbers to be essential clean up crew members for a reef tank with a deep sandbed. They will keep the top half-inch of substrate detritus and algae free by “vacuuming” the sand. Somewhat reclusive, th

Some hobbyists consider sea cucumbers to be essential clean up crew members for a reef tank with a deep sandbed. They will keep the top half-inch of substrate detritus and algae free by “vacuuming” the sand. Somewhat reclusive, they are often most active at night. They can emit a toxin if harassed that can kill fish and other invertebrates.